Jan, thanks for the reply on the prop question. Is there a source where I could find a formula for computing the thrust of different props and pitch combinations? Thanks to the guys for the other replys also. I have looked quite a bit at creating power with a direct drive LS engine. The turbo certainly has its benefits, but it does add some weight and lots of heat to deal with. Then tuning the engine to work with it becomes somewhat complicated. In the instance I'm looking at, I will be trying to build as simple a combination as possible and most likely use injection. I want to emulate an aero engine with low rpms. Weight will be a major concern in the airplane I want to build......so anything that adds even more weight is a non-consideration for me. The LS6 engines are hard to find and have been surpassed by the newer LS versions. The LS7 complete is way too expensive for most people ($13000). On the other hand, if someone purchased a readily available LS3 type block with a 4.000 inch stroker crank, they would have 415 cu in. Cubic inch increase is the easist way to increase power in these blocks with minimal change in weight. Cost for the assembled block/crank/pistons is about $4200. Since you don't need high flowing heads, used LS1 heads should provide all the air needed for an engine only turning 2700 rpms. I have talked to some knowledgeable automotive industry experts and they agreed with my concept and even gave me some suggestions for cam choices. Something also available is the Cam Calculator that Comp Cams has on line. You might play with that a little. To buy a new complete LS1 these days will probably run you about $5800. Going the stroker route would allow you to basically assemble an engine for $7000 that had far more power for the same weight. You can easily find used LS1 heads for $200 (or less) an intake with injectors for anothe $200 or less. Buy a new cam and lifters and a Rattler or Fluid Damper.......and you have a much more usuable combo. Did I mention that the rotating assembly will also be more robust than the factory units? Now look at some of the new plug and play computers or SDS and you have a purpose built combo that will easily produce 235/260 hp @2700 rpms. Also, the compression ratio can be selected to run cheap gas wwith a 9.5 comp ratio vs the higher stock LS1 ratio. Now, the question becomes how to couple all the power I need for my particular airplane, to the propeller. This is why I feel a direct drive with a short shaft coupling will save weight and a reduction drive ($5-7K) (80 lbs) is not the best choice......for me anyway.